1. Field of the Invention
This invention relates to semiconductor devices, and more particularly to surface-mount packages for integrated circuit devices.
2. Description of the Prior Art
Integrated circuit devices have been housed in dual-in-line plastic packages, referred to as DIP packages, in the bulk of semiconductor manufacture, for many years. These DIP packages have leads which extend through holes in a printed circuit board (PCB), and the package itself is mounted flat on the board. More recently surface-mount packaging has been introduced, and this technique eliminates the necessity of soldering leads in holes in PC boards, so the leads and PC board conductors can be closer together and higher densities are achieved. Similarly, edge-mounted packages or modules have been used in an effort to further increase the density of devices, improve cooling and reduce cost. As the density of devices and circuitry on the dies continues to increase, the packing density must also increase, both at the package level and at the board level, while at the same time providing adequate cooling, and allowing the assembly and soldering of packages and boards to be fast, accurate and nondestructive. In particular, the packaging technique must provide protection for the leads during test, burn-in, and transport, as well as ease of positioning and mechanical support during mounting and soldering and during the life of the system.